>From personal experience, 0.1mA is wa-a-a-ay too high!
Make it more like 10 uA
- Robert -
On Tue, 11 Oct 2005 18:03:19 +0100
[email protected] wrote:
> With regard to whether Doug should be measuring Patient
> Leakage from his
> bedframe:-
>
> I believe the bedframe is an Applied Part under the
> definition of the
> general standard 60601-1; ("AP = a part of the equipment
> which in normal use
> .....can be brought into contact with the patient ....")
> ie: contact isn't
> necessary for the device to perform its function, but
> contact could happen
> during use - which is the case for hospital bedframes.
>
> Under the particular standard for electric beds
> IEC-60601-2-38, "AP = all
> parts of the bed which can intentionally or
> unintentionally come into
> contact with the patient..."). There is a diagram in the
> edition we have
> (1996) showing which areas of the bedframe are thus
> included.
>
> My interpretation is then that the bedframe should be
> considered an AP and
> so, as Doug says, it should be tested for Patient
> Leakage. If it were not an
> AP it would have to be tested for Enclosure Leakage
> anyhow - in both cases
> the limits for ac leakage are 0.1mA Normal Condition and
> 0.5mA Single Fault
> Condition (though for Patient Leakage there are dc limits
> too).
>
> If you are measuring 0.1mA leakage through the specified
> measuring device,
> which simulates a patient impedance, then how low the
> voltage is on the
> earthed frame is kind of immaterial - it is the current
> not the voltage that
> the patient will feel. (The leakage likely has high
> impedance origins which
> are better modelled as a current source than a voltage
> source).
>
>
> Ged Dean
>
-
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